This invention relates to a method and apparatus for horizontal drilling into the earth strata surrounding a well casing. More specifically, the present invention relates to a method and apparatus for drilling through the walls of a vertically extending well casing at a 90.degree. angle to provide horizontal drilling into the earth's strata for a substantial distance radially from the vertically extending well casing.
Oil and gas wells are drilled by the use of rotary drilling equipment vertically into the earth's strata. The vertically extending well holes generally include a casing usually of mild steel in the neighborhood of 41/2 inch (11.4 cm) to 8 inch (20.3 cm) in diameter which define the cross-sectional area of a well for transportation of the oil and gas upwardly to the earth's surface. However, these vertically extending wells are only useful for removing oil and gas from the general vicinity adjacent to and directly underneath the terminating downward end of the well. Thus, not all of the oil and gas in the pockets or formations in the earth's strata, at the location of the well depth, can be removed. Therefore, it is necessary to either make other vertical drillings parallel and close to the first drill, which is timely and costly, or provide means to extend the original well in a radial or horizontal direction. The most common means for horizontal extension of the well has been to drill angularly through the well casing at a first 45.degree. angle for a short distance and then to turn the drill and drill at a second 45.degree. angle thereby making a full 90.degree. angular or horizontal cut from the vertically extending well. These horizontal drills have proved useful for extending the well horizontally. However, most of these horizontally extending cuts have proved to be relatively expensive.
There have been a number of patents issued which teach a number of different ideas for accomplishing horizontal drillings or cuttings into the earth's strata surrounding an existing well, but, again, most of these have proved to be costly and have also not produced the desired results. U.S. Pat. No. 4,640,362 teaches a method of penetrating a well casing and surrounding earth strata with the use of a punch member for cutting through a well casing wherein the punch member includes a retractable jet nozzle means therein for penetrating the surrounding earth's strata after the punch member has cut through the casing. Moreover, U.S. Pat. No. 4,185,705 teaches a well perforating tool for drilling holes in a well casing which includes an upset tubing with a downward terminating end curving laterally away from its longitudinal axis and terminating in a threaded end portion that passes through a correspondingly shaped aperture formed in the wall of the well casing. Other patents which teach drilling components for horizontal extensions from vertically extending wells wherein hydraulic fluid directing nozzles are used in the drilling operations include U.S. Pat. No. 2,271,005; U.S. Pat. No. 2,345,816; U.S. Pat. No. 3,838,736; U.S. Pat. No. 3,873,156; and, U.S. Pat. No. 4,168,752.